Anyone any good (or have some idea) at science? Cookies up for grabs!

[SuperCoblet]

Completely not horsey, doing my Exams and I've been sat looking at this book for about an hour now, completely stunned on how confused I am! Anyway, as soon as I say chemistry I see everyone scrambling away already basicly I have to write an assessment report and have a whole page of bullet points to write about D:
Ready? It says:
Describe magnesiums atomic number and mass number in terms of protons and neutrons.
Explain the concept of isotopes using magnesium-24 (79%), magnesium-25 (10%) and magnesium-26 (11%)

Yes, I'm confused! Please help de-stress me lots and lots of wine and cookies!

 

[Queenbee87]

I'm a bit too rusty to be of any use but you may find you get a better response posting in soapbox or common room? Good luck

 

[daydreamer]

The atomic number determines which element something is, it is the number of protons. The mass number is the mass of an atom and is the number of protons plus the number of neutrons. If you find a periodic table the symbol for magnesium should have 2 numbers by it, the larger one is the atomic mass and the small one the atomic number. (can't remember exactly off the top of my head but think it is 12 and 24!)

Isotopes are atoms of the same element with different mass numbers. I.e. they all have the same number of protons but the number of neutrons differs. Magnesium has 3 isotopes, i.e. three slightly different versions. The % abundance is how much of the sample is made of that type of isotope. It is possible to calculate the average mass of an atom of magnesium by taking into account all these different isotopes. This average mass is called the relative atomic mass.

To calculate the relative atomic mass do the (mass of isotope 1 x abundance of isotope 1) + (mass isotpe 2 x abundance isotope 2) + (mass 3 x abundance 3) then divide that number by 100.

 

[Sirreal]

hi
the atomic number of magnesium is the number of protons in its nucleus. the mass number is the combined numbers of protons and neutrons.

isotopes: the same element (so the same amount of protons in the nucleus) but different numbers of neutrons. this means they will have slightly different mass numbers, but are still the same element.
each sample of magnesium will contain different isotopes.

Explain the concept of isotopes using magnesium-24 (79%), magnesium-25 (10%) and magnesium-26 (11%)

79% of the sample is made up of magnesium with the mass number 24, 10% with mass number 25, 11% with mass number 26. this shows you that magnesium-24 is the most common element. isotopes can also be radioactive.

hope this helps! it's hard to answer without seeing the actual question and context. if you need any more help just ask
xxxxx

 

[saz5083]

Ok, I'll see if I can help
The atomic number of an element is the number of protons in an atomic nucleus, the mass number is the number of protons + the number of neutrons. So Mg has an atomic number of 12 and a mass number of 24 (most of the time!) which means it has 12 protons and 12 neutrons.
Isotopes are basically variations of an element where the neutron number changes but the designation of the molecule as a particular element doesnt. So in your example, Mg24 is the most common form of magnesium (with 12 protons and 12 neutrons), Mg25 makes up 10% of the naturally occurring magnesium and has 13 neutrons (12+13=25), while Mg26 makes up 11% of naturally occurring magnesium and has 14 neutrons (12+14=26).
Does that make sense?

 

[SuperCoblet]

Thanks everyone! Just managed to scramble down anything, don't know if it makes sence bit hey *throws a pack of virtual cookies to everyone*

So, more bullet points! Run!!
Explain why an atom of magnesium has no overall charge.
And I think I know the rest, thankyou everyone, you saved my life from very grumpy Ginger teacher

 

[dafthoss]

It has no overall charge as it has the same number of protons and electrons. Good luck it's been ages since I did my chemistry but I too had a Ginger chemistry teacher who was extremely grumpy

 

[**Vanner**]

all atoms have no charge because the number of protons (+1 charge) equals the number of electrons (-1 charge).

When an ion is formed an atom loses or gains electrons and so becomes charged accordingly.